Method of printing

ABSTRACT

A method of printing information on each article of a set of articles arranged in generally parallel lanes at a printing station, the method including continuously moving a printing apparatus relative to the lanes to bring the printing apparatus into registry with each article of the set in turn, and at each registry position, whilst continuing to move the printing apparatus, moving a print head of the apparatus relative to the respective article to a printing position in which the print head is capable of printing information on the article, continuing to move the printing apparatus relative to the article whilst effecting printing with the print head, and when the information is printed, whilst continuing to move the printing apparatus, moving the print head out of the printing position.

DESCRIPTION OF INVENTION

This invention relates to a method of printing.

It is a requirement to be able to print on each article of a set ofarticles which are conveyed to a printing station in generally parallellanes.

For example in a packaging line, a plurality of articles on each ofwhich it is desired to print information, may be conveyed side by sideon a conveying means, to a printing station where the information is tobe printed.

So called intermittent printers are known in which a print head is movedrelative to a stationary substrate whilst printing elements of the printhead are actuated to print desired information on the substrate. Suchprinters may be thermal printers in which pixels of ink are removed froma ribbon as the printing elements are energised, and thus the printhead, during printing, moves not only relative to the substrate, butrelative to the ribbon too.

By virtue of the need to move the print head relative to the stationarysubstrate, the length of information which can be printed along thestationary substrate is restricted.

It is known to use an intermittent printer of the type described above,to achieve printing on each article of a set of articles which areconveyed side by side in generally parallel lanes to a printing stationwhere the printer is located. The printer is mounted on a carriage andis bodily conveyed transversely across the lanes. The articles aremaintained stationary at the printing station and the printer isconveyed transversely of the lanes to a first position where movement ofthe printer is stopped, and then printing is effected on a first of thearticles by moving the print head within the stationary printingapparatus. The printer is then conveyed transversely of the lanes to asecond position where movement of the printer is again stopped, so thatprinting may be effected on a second article, and so on for all of thearticles of the set.

Although intermittent printers are not particularly fragile, thecontinual stopping and starting of the carriage creates wear and tear onthe intermittent printer. The problem is aggravated because of the speedat which it necessary to convey the printer between stops in order toreduce the time between printing on the articles to a minimum. Thus notonly is the printer subjected to jolts as the printer stops, but rapidaccelerations when the printer is moved between stops. Also, thecarriage and its ancillary drive system is subject to wear and tearaggravated by the start/stop motion of the printer.

So called continuous thermal printers are also known in which a printhead is held stationary at a printing station and during printing, thesubstrate and ribbon are moved past the print head, usually together,whilst the printing elements of the print head are selectivelyenergised, to effect printing. The length of print is not restricted asin an intermittent printer because the print head is not moved in theprinter, but relative movement between the print head, and the ribbonand substrate, is achieved solely by movement of the ribbon andsubstrate. Such printers tend to be used where the substrate is a movingweb, which can readily be moved together with the ribbon past the printhead, whereas intermittent printers are more readily adaptable forprinting on other substrates such as articles on a packaging line,because relative movement between the print head, and the ribbon andsubstrate, is achieved by print head movement.

According to one aspect of the invention we provide a method of printinginformation on each article of a set of articles arranged in generallyparallel lanes, at a printing station, the method including continuouslymoving a printing apparatus relative to the lanes to bring the printingapparatus into registry with each article of the set in turn, and ateach registry position, whilst continuing to move the printingapparatus, moving a print head of the apparatus relative to therespective article to a printing position in which the print head iscapable of printing information on the article, continuing to move theprinting apparatus relative to the article whilst effecting printingwith the print head, and when the information is printed, whilstcontinuing to move the printing apparatus, moving the print head out ofthe printing position.

Thus utilising the invention, it is unnecessary to arrest movement ofthe printing apparatus as the printing apparatus moves across the lanesof articles, but at each registry position, it is only necessary to movethe print head within the printing apparatus to the printing position.Thus the problems mentioned above with using an intermittent type ofprinter in this context are largely overcome.

Preferably the printing apparatus is mounted on a carriage and themethod includes continuously moving the carriage, preferably at agenerally constant speed, transversely across the lanes, relative to abase structure relative to which each of the articles of the set is heldstationary during printing. All of the articles of the set may bepositioned at the printing station simultaneously whilst the printingapparatus is moved transversely across all the lanes, or the articlesmay be conveyed severally, e.g. in turn, in their respective lanes, tothe printing station, provided that the articles each are present at theprinting station so that the printing apparatus may be moved intoregistry with the articles and printing performed, whilst the printingapparatus is continuously moved.

The printing apparatus may include a housing mounted on the carriage,and print head movement to and from the printing position may berelative to the housing of the printing apparatus.

The print head may be of the kind having a plurality of printingelements which are selectively actuated during printing by a controlmeans to effect printing of desired information on each of the articles.The information printed may be the same for each of the articles, ordifferent for at least one of the articles compared with the otherarticles.

In one embodiment the printing apparatus is a thermal printer in whichthere are printing elements arranged in a generally linear array alongthe print head with the array extending generally transversely to thedirection of movement of the printing apparatus across the lanes, themethod including selectively energising the printing elements duringprinting to remove pixels of marking medium such as a thermal ink, froma carrier positioned between the printing elements and the article. Thusin moving the print head to the printing position, the printing elementsare brought into a position in which the elements, when energised, areable to remove pixels of marking medium from the carrier, and when theprint head is moved out of the printing position e.g. away from thearticle, the printing apparatus may be moved relative to the articlewith the printing elements out of contact with the carrier or at leastwith the carrier out of contact with any of the articles.

The method may include moving the carrier relative to the print head asthe printing apparatus moves transversely of the lanes of articlesduring printing, so as that fresh carrier may continually be positionedbetween the print head and the article on which information is beingprinted. By “fresh” carrier we mean a new area of carrier from whichpixels of marking medium to be moved during subsequent printing have notbeen removed in previous printing.

The printing apparatus may include a housing within which there isprovided a storage spool for unused carrier, a take-up spool for usedcarrier, a first motive means to move at least the take-up spool to takeup used carrier, and a second motive means to move the print head to andfrom the printing position.

In one arrangement, the method may include conveying the articles of theset in their parallel lanes to the printing station, arresting movementof the set of articles at the printing station while the information isprinted on each of the articles of the set.

According to a second aspect of the invention we provide a method ofprinting information on each article of a set of articles arranged ingenerally parallel lanes, at a printing station, the method includingcontinuously moving a printing apparatus relative to the lanes to bringthe printing apparatus into registry with each article of the set inturn, the printing apparatus including a print head and a carrier formarking medium which is applied to the articles during printing, and ateach registry position, whilst continuing to move the printingapparatus, effecting printing with the print head, and when theinformation is printed, continuing to move the printing apparatus to thenext registry position.

The invention may be applied to a thermal print head in which printingelements are selectively energised during printing to melt and removepixels of marking medium from the carrier and deposit the pixels of inkon to the articles. Alternatively, the invention may be applied to analternative kind of printer, such as an ink jet type printer in whichthe marking medium is contained in a reservoir and selectively appliedby jetting, onto the articles to print the information.

The method of the second aspect of the invention may have any of thefeatures of the method of the first aspect of the invention.

According to a third aspect of the invention we provide a printingstation for performing the method of the first or second aspect of theinvention, the printing station including a carriage, a printingapparatus, means to mount the printing apparatus on the carriage, meansto move the carriage and thus the printing apparatus transversely of aplurality of lanes and to effect printing on each of a plurality ofarticles at the printing station, each of the articles being located inone of the lanes, characterised in that the means to move the carriageis adapted to move the carriage substantially continuously across thelanes and the printing apparatus being adapted to print the informationon each of the articles of the set in turn without or substantiallywithout stopping.

In one embodiment, the carriage may be mounted on a gantry which extendsover or under the lanes and the printing apparatus is moved over orunder the lanes respectively, on the carriage.

The gantry and/or the carriage may include a drive means for moving thecarriage, as desired. Movement of the carriage may be controlled by acontrol means which co-ordinates printing with carriage movement.

The invention will now be described with reference to the accompanyingdrawings in which:

FIG. 1 is a side illustrative view of a printing station which may beoperated in accordance with the invention, at the commencement ofprinting on each article of a set of articles;

FIG. 2 is an illustrative plan view of the printing station of FIG. 1but after printing.

Referring to the drawings, a printing station 10 is located adjacent aconveying means 12 e.g. of a packaging line, the conveying means 12being arranged to convey sets of articles, two of which are shown at 14a to 14 e and 15 a to 15 e, to and from i.e. past the printing station10, with the articles arranged in generally parallel lanes a to e. Thusthe articles of a set, e.g. articles 14 a to 14 e are, at the printingstation 12, side by side. In this example, the articles 14 a to 14 e ofthe set all arrive at the printing station 10 together, although theymay arrive severally, provided that each article 14 a to 14 e is presentat the printing station 10 prior to a printing apparatus 16 being movedas hereinafter described, into registry with the articles, for printing.

In the example illustrated, the conveying means 12 is a belt or rollerconveyor on which the articles 14 a to 14 e and 15 a to 15 e are movedrelative to a base structure 21, but the invention may be utilised withother kinds of conveyor which are adapted to deliver a set of articlesin lanes to a printing station 10.

As shown, the printing station 10 includes a gantry 18 mounted on thebase structure 21 relative to which the conveying means 12 conveys thearticles 14 a to 14 e and 15 a to 15 e, the gantry 18 having upstandingsupports 19 at either side of the conveying means 12, and a generallyhorizontal rail part 20 although any other construction, e.g. asuspended construction, may be used to provide a rail or the like alongwhich a carriage 22 carrying the printing apparatus 16 may be provided.

The carriage 22 is in this example suspended from the gantry rail part20, but may be mounted on the rail part 20, or the rail part may bearranged to pass through the carriage 22 as desired. The carriage 22 haswheels or rollers 24 which ride on the rail part 20 to facilitatecarriage 22 movement along the rail part 20. The carriage 22 in thisexample includes a drive means (not shown) which applies drive, througha suitable transmission (not shown) to the wheels or rollers 24 toeffect carriage 22 movement along the rail part 20 transversely of thelanes a to e of articles 14 a to 14 e and 15 a to 15 e. In anotherembodiment, the carriage 22 may be driven by an external drive means,such as a motor connected by cables to the carriage 22, or by a leadscrew with which a threaded member of the carriage 22 co-operates.

The requirement is for the carriage 22 to be moveable transversely of aset of articles 14 a to 14 e positioned at the printing station 10,preferably in a continuous or substantially continuous movement ashereinafter described.

The carriage 22 is fixed relative to the print apparatus 16, and theprinting apparatus (16) includes a housing 25 in which is contained aprint head 26 which in this example is a thermal print head 26 having alinear array 27 of thermal printing elements 28 each of which mayselectively be energised under the control of a control means 30, suchas computer, to remove pixels of marking medium such as a thermoplasticink, from a carrier ribbon 31, as the print head 26 and ribbon 31 arerelatively moved, and to deposit the ink onto an adjacent article.

The ribbon 31 is provided on a supply spool 32 mounted in the housing25, and is wound on to a take-up spool 33 in use. In this example, thetake-up spool 33 is driven from its own motive means 34 e.g. via a belt35 or gear drive. In another example, the take-up spool may be drivenfrom the drive means of the carriage 22.

The ribbon 31 is located between the print head 26 and an article 14 ato 14 b of the set of articles onto which information is to be printed,and the print head 26 is movable by a motive means (not shown) formovement towards and away from the articles 14 a to 14 e as indicated inFIG. 1 by the arrow A. When moved towards an article 14 a to 14 e, asseen in FIG. 1, to a printing position, the ribbon 31 is urged intocontact with the article and as the printing elements 27 are selectivelyenergised, the ink is melted and transferred from the ribbon 31 on tothe article. When the print head 26 is moved away from the article outof the printing position, relative movement occurs between the printhead 26 and the article 14 a to 14 e without any ink being removed fromthe ribbon and deposited on to an article, as the ribbon will be out ofcontact with the article, and typically out of contact with the printhead 26 too.

The control means 30 in this example is connected to the printingapparatus 16, and to the drive means of the carriage 22 as desired, viaa travelling lead 37, as is well known in the art, although the controlmeans 30 or part of the control means may be mounted in or on theprinting apparatus 16 or carriage 22 as desired.

A method in accordance with the invention will now be described.

A set of articles, 14 a to 14 e are conveyed by the conveying means 12to the printing station 10, where they are held stationary. This may beachieved by the control means 30 co-ordinating article movement to stopthe conveying means 12 when the articles 12 a are in the positions shownin FIG. 1, or else some physical barrier may be moved into the path ofthe articles 14 a to 14 e to arrest further movement of the articles 14a to 14 e.

The carriage 22 and printing apparatus 16 are then moved transversely ofthe lanes a to e of the articles 14 a to 14 e with the print head 26moved out of the printing position. When the printing apparatus 16 hasbeen moved to a position in registry with a first article 14 a of theset of articles such that the print head 16 is positioned over a part ofthe article where it is desired to print information, the print head 26is moved towards the article 14 a into the printing position as seen inFIG. 1, with the ribbon 31 urged into contact with the article 14 abetween the print head 16 and the article 14 a, while movement of thecarriage 22 and printing apparatus 16 across the lanes a to e continues.

Printing of the information on the article 14 a may then be commenced.The ribbon 31 will need to be moved by its motive means 34 relative tothe print head 16 during printing. Such ribbon 31 movement may be at aspeed such that the ribbon 31 and article 14 a are or are not relativelymoving, as desired to achieve a required quality of print. The printingelements 28 will selectively be energised as the carriage 22 and printhead 16 continues to move transversely of the lanes a to e to print thedesired information. When the information has been printed, the printhead 16 is moved away from the article, again while print head 16 andcarriage 22 movement transversely of the lanes a to e continues.Preferably ribbon 31 movement relative to the print head 16 is arrestedso as not to waste ribbon 31.

The method is repeated as the printing apparatus 16 is moved intoregistry with a second 14 b of the articles 14 a to 14 e, and then foreach of the remaining articles 14 c to 14 e.

All the time, the printing apparatus 16 and carriage 22 continue to movetransversely of the lanes a to e such that there is no requirement tostop the printing apparatus 16 until information has been printed on allof the articles 14 a to 14 e of the set.

When the printing apparatus 16 has printed on the last article 14 e ofthe set, the conveying means 12 may be operated, or any physical barrierpresent removed, to permit the articles 14 a to 14 e all to be conveyedin their lanes a to e beyond the printing station 10 as illustrated inFIG. 2, so that the next set of articles 15 a to 15 e may be conveyed tothe printing station 10 for printing. If desired, as the next set ofarticles 15 a to 15 e are conveyed to the printing station 10, theprinting apparatus 16 and carriage 22 may be moved back across the lanesa to e ready to print on the first article 15 a of the next set, in thefirst lane a. Alternatively, the information may be printed on each ofthe next set of auricles 15 a to 15 e in a reverse order as the printingapparatus 16 and carriage 22 are moved transversely of the lanes a to ein an opposite direction to the direction of movement of the printingapparatus 16 and carriage 22 during printing on the articles 14 a to 14e of the previous set. In each case though, it is necessary to move theribbon 31 relative to the print head 26 during printing so that freshribbon 31 from which pixels of ink have not already been removed, iscontinually presented between the print head 26 and the articles onwhich information is to be printed.

Various modifications in addition to those already mentioned may be madewithout departing from the scope of the invention. For example, asdescribed the invention has been applied to a printing apparatus of thethermal kind, although may be applied to any other printing apparatus,such as an ink jet or other pixel based printing apparatus, as desired.Thus in such an alternative arrangement, a carrier ribbon for ink maynot be required, but the ink may be contained in a carrier reservoirfrom which it is fed to printing elements or jets of the print head forjetting on to the articles during printing. The invention may be appliedto other pixel based and non pixel based systems as desired.

Although in the drawings, a conveying means 12 for conveying a set offive articles is indicated, or course the set of articles may be anyplurality of articles in a corresponding number of lanes.

The features disclosed in the foregoing description, or the followingclaims, or the accompanying drawings, expressed in their specific formsor in terms of a means for performing the disclosed function, or amethod or process for attaining the disclosed result, as appropriate,may, separately, or in any combination of such features, be utilised forrealising the invention in diverse forms thereof.

1. A method of printing information on each article of a set of articlesarranged in generally parallel lanes, at a printing station, the methodcomprising: providing the printing station including a gantry, acarriage mounted to the gantry, and a printing apparatus having ahousing mounted on the carriage, and a print head, the printingapparatus being movable transversely across the lanes; continuouslymoving the printing apparatus transversely across the lanes to bring theprinting apparatus into registry with each article of the set in turn;at each registry position, whilst continuing to move the printingapparatus, moving the print head of the apparatus relative to thehousing and relative to the respective article to a printing position inwhich the print head is capable of printing information on the article;continuing to move the printing apparatus transversely relative to thearticle whilst effecting printing with the print head; and when theinformation is printed, whilst continuing to move the printing apparatustransversely, moving the print head relative to the housing out of theprinting position.
 2. A method according to claim 1 wherein the printingapparatus is continuously moved across the carriage transversely acrossthe lanes, relative to a base structure relative to which each of thearticles of the set is held stationary during printing.
 3. A methodaccording to claim 2 wherein the carriage is moved transversely of thelanes at a generally constant speed.
 4. A method according to claim 1wherein all of the articles of the set are positioned at the printingstation simultaneously whilst the printing apparatus is movedtransversely across all the lanes.
 5. A method according to claim 1wherein the articles are conveyed severally in their respective lanes,to the printing station, and are arranged to be present at the printingstation so that the printing apparatus may be moved into registry withthe articles and printing performed, whilst the printing apparatus iscontinuously moved.
 6. The method according to claim 1, wherein thearticles are unconnected and spaced from each other along the generallyparallel lanes.
 7. A method according to any claim 1 wherein the printhead is of the kind having a plurality of printing elements which areselectively actuated during printing by a control means to effectprinting of desired information on each of the articles.
 8. A methodaccording to claim 1 wherein the printing apparatus is a thermal printerin which there are printing elements arranged in a generally lineararray along the print head with the array extending generallytransversely to the direction of movement of the printing apparatusacross the lanes, the method including selectively energising theprinting elements during printing to remove pixels of marking mediumfrom a carrier positioned between the printing elements and the article.9. A method according to claim 8 wherein the method includes moving thecarrier relative to the print head as the printing apparatus movestransversely of the lanes of articles during printing, so as that freshcarrier is continually being positioned between the print head and thearticle on which information is being printed.
 10. A method according toclaim 8 wherein the printing apparatus includes a housing within whichthere is provided a storage spool for unused carrier, a take-up spoolfor used carrier, a first motive means to move at least the take-upspool to take up used carrier, and a second motive means to move theprint head to and from the printing position.
 11. A method according toclaim 1 which includes conveying the articles of the set in theirparallel lanes to the printing station, arresting movement of the set ofarticles at the printing station while the information is printed oneach of the articles of the set.
 12. A method of printing information oneach article of a set of articles arranged in generally parallel lanes,at a printing station, the method comprising: continuously moving aprinting apparatus relative to the lanes to bring the printing apparatusinto registry with each article of the set in turn, the printingapparatus including a print head and a carrier for marking medium whichis applied to the articles during printing; at each registry position,whilst continuing to move the printing apparatus, effecting printingwith the print head; and when the information is printed, continuing tomove the printing apparatus to the next registry position.
 13. A methodaccording to claim 12 wherein the method is applied to printingapparatus having a thermal print head having printing elements which areselectively energised during printing to melt and remove pixels ofmarking medium from the carrier and deposit the pixels of ink on to thearticles.